The world No. 5 won 6-3 6-3 4-6 4-6 6-3 in the semifinal against Zverev at Roland Garros.
Having blitzed into a two-set lead, world No. 6 Zverev produced a stirring comeback to win the third and fourth sets, but after regrouping, Tsitsipas came back with a bang, winning the decisive set.
The 22-year-old Tsitsipas will now face either Rafael Nadal or Novak Djokovic in Sunday’s final.